I am counting the days for my first
Disney cruise and can help with a couple of questions.
You will have to pay a deposit when you book the trip - the amount depends on the amount of your trip but is usually around 20% I believe. Then, you have to make the full payment 75 days before you sail (for everything except suites, those are 90 days).
You are able to make as many smaller payments as you want between the time you book and 75 days out. So, if it works for you, you can pay monthly instead of all at once.
One other option - the one I did - was to use the DIsney Visa to pay for the trip. You get 6 months free interest for each payment to Disney Cruise. For example, I paid the deposit last September and had until February to pay that amount interest free. Then, I paid the balance of the cruise in November and have until May to pay that amount interest free.
This also has an added benefit that if you use your Disney Visa to pay for the whole cruise you currently receive a $50 on board credit. This can be used for tips, excursions, etc... and is a nice little bonus. There is also a $25 OBC credit if you book it yoursef online through the Disney Cruise website.
Hope this helps!